Quis custodiet ipsos custodes?
Quis custodiet ipsos custodes? is a Latin phrase that translates to "Who will guard the guards?" or "Who shall watch the watchers themselves?"
The question was first asked by Plato in the Republic, his great work on government and morality. The perfect society as described by Socrates, the main character of the work, relies on laborers, slaves, and tradesmen. The guardian class is to protect the city. The question is put to Socrates, who will guard the guardians? or, who will protect us against the protectors? Plato's answer to this is: they will guard themselves against themselves. We must tell the guardians a noble lie. The noble lie will inform them that they are better than those they serve and it is, therefore, their responsibility to guard and protect those lesser than themselves. We will instill in them a distaste for power or privilege, they will rule because they believe it right, not because they desire it.
The saying has since been used by many people to ponder the insoluble question of where ultimate power should reside. The answer for the United States was found in the separation of powers. Never give ultimate power to any one group; the executive, legislative, or judicial; have the interests of each compete and conflict. Each group will then find it in its best interest to impede the functioning of the rest and this will keep ultimate power under constant struggle and, thereby, out of any one group's hands.